1. Field of the Invention
The present invention relates to a PABX (Private Automatic Branch eXchange) and keyphone system, and more particularly to a method for automatically detecting an abnormal state on a speech path of a PABX or keyphone system.
2. Description of the Related Art
Generally, a PABX (Private Automatic Branch eXchange) is a system that forms a speech path between a trunk line connected to a central office line and extensions connected to extension subscribers, or a speech path among the extension subscribers, to provide a call service to the extension subscribers. However, such a system has a problem that if a trunk port or extension port of the system is abnormal, no speech service may be provided to a subscriber connected to the abnormal port.
In order to solve the above problem, a conventional line tester has been installed in a switching board, as in a subscriber circuit of the exchange, to detect whether a subscriber line from the subscriber circuit to a subscriber module is in an abnormal state by manually testing whether the subscriber module and subscriber circuit are normally operated. The conventional line tester includes a test relay for testing operating states of the subscriber module and subscriber circuit. However, the above-mentioned conventional line tester has a disadvantage in that it is low in performance, resulting in waste of test time, high cost due to wasted labor costs, service quality deterioration due to testing during working hours, and the like. Further, a separate test relay must be provided for each subscriber line from the subscriber card, resulting in high cost being incurred. Moreover, the conventional line tester is designed to operate equipment to be tested and test it in every direction, thereby making it very hard to automatically test the equipment.
This application makes reference to, incorporates the same herein, from my application METHOD FOR TESTING SUBSCRIBER LINE OF PRIVATE AUTOMATIC BRANCH EXCHANGE USING DUAL-TONE MULTI-FREQUENCY SIGNAL filed with the Korean Industrial Property Office on Jan. 16, 2001 and there duly assigned Serial No. 2001-2386 and laid-open on Jul. 24, 2002 with Publication No. 2002-61360.